1. Field of the Invention
The present invention relates to a preset counter apparatus for use, for example, in copying machines for setting and displaying the number of copies to be made continuously.
2. Description of the Prior Art
Preset counters heretofore generally used in copying machines for setting the number of copies to be made continuously are those of the mechanical rotary type comprising, for example, a setting dial and a ratchet wheel in combination. The dial is rotated by one division of its scale for every copying cycle and adapted to turn off a switch for continuing the copying operation when rotated to its final position. However, mechanical counter apparatus of this type require a mechanical coupling mechanism for driving the apparatus as associated with the copying operation, have the drawback of being complex in construction and expensive, are prone to malfunctions and are limited approximately to 20, if largest, in the number of copies to be set. Thus the use of the apparatus involves many problems.
On the other hand, with the progress of electronic technologies in recent years, IC, LSI and like elements are made available with an increased degree of integration and performance of enhanced stability at reduced costs. These elements are widely used for controlling mechanical apparatus, such as copying machines. Such elements have also found use in electronic counters, which are in combination with seven-segment number displays for indicating the count of the counter to provide preset counter apparatus.
When electronic counters are used, the number of copies is set by ten keys for setting the numbers "0" to "9". In the case where the circuit or program for the counter is designed according to a comparison system, the set value is stored in a memory, and a signal emitted every copying cycle is counted. When the count matches the stored value, the copying operation is discontinued. (U.S. Pat. No. 3,815,990, Newcomb et al., discloses this system although the counter disclosed is not of the electronic type.) Alternatively when a subtraction system is resorted to, a decrement is subtracted from the value set on the counter for every copying cycle, and the copying operation is discontinued when the count on the counter has reduced to "0" (U.S. Pat. No. 4,105,914, Murata et al.). In either case, the counter is associated with the copying operation only electrically, while the maximum number of copies to be made can be selected as desired, so that the electronic counter is free of many of the problems encountered with the foregoing mechanical counter apparatus. Accordingly counter apparatus incorporating such an electronic counter or program control system are widely used in copying machines, etc.
However, with LSI.degree. s, microcomputers, etc. coming into wider use, copying machines and the like including electronic counters of this type are adapted for more versatile functions with a larger number of keys or displays for the instructions or selection by the user, while there arises a tendency to provide these keys and displays concentrically on a single operation panel to render the machine easy and efficient to operate. This leads to an increase in the area of the operation panel, a greater likelihood of handling or manipulation errors and an increased cost. These new problems are difficult to overcome especially in the case of compact copying machines in which only a limited space is available on the operation panel and which also involve limitations in respect of cost.
To solve the above problems, an apparatus has been proposed which has three input keys, namely UP key, DOWN key and CLEAR key, as disclosed in Published Unexamined Japanese Patent Application Sho No. 54-145545 (1979). Every time the UP key or DOWN key is depressed or when the key is held depressed, the numerical value shown on a seven-segment number display is increased or decreased, while the CLEAR key, when depressed, returns the displayed value to "1".
The proposed apparatus nevertheless is very cumbersome to use since when the number of copies to be set is large, the key must be depressed a large number of times or held depressed for a prolonged period of time.